+ / - Coil Wiring Colours - '01 VL 800

I finally got round to start fitting the tacho on my '01 VL. Picked up the feeds OK (dead easy with the auxiliary fuse box), & decided to just wrap the pick-up wire around the plug lead (being a bit lazy & it was easy to get to) - of course it didn't work !!! (Well the lights came on & it did a needle-sweep) So now I'm going to go for twojobs suggestion of the pos terminal on the coil. On both coils I have orange/white lead, the front coil also has a black/yellow lead, the rear has a white lead. Which one is the positive ? I'm guessing that the orange/white is the negative, but the wiring diagram doesn't make it clear - why on earth don't they use one colour all the way through for the earth cabling ??

Thanks for that Dave - I'll give it a go. I don't suppose it's gonna harm it if it gets connected to the negative !!!

I've just rang Suzuki GB to ask the question of their technicians - won't answer the question in case the wiring has been changed at some point !! They want me to take the bike to my local dealer for them to investigate - I remember how useful they were when I wanted them to change the seal on the diff unit !!